Question

I expect that code to display “New Version” at every 3 seconds but it doesn’t.

Car.h

#import <Foundation/Foundation.h>

@interface Car : NSObject


-(void)displayVersion;
@end 

Car.m

#import "Car.h"

@implementation Car

-(void)displayVersion
{
    NSLog(@"New version");
}

@end

main.c

#import <Foundation/Foundation.h>
#import "Car.h"

int main (int argc, const char * argv[])
{
    @autoreleasepool 
    {
        Car *ford = [[Car alloc]init];

        [NSTimer scheduledTimerWithTimeInterval:3 
                                         target:ford
                                         selector:@selector(displayVersion) 
                                         userInfo:nil 
                                         repeats:YES];
    }
    return 0;
}

What is wrong here ?

PS: I hate that “Your post does not have much context to explain the code sections; please explain your scenario more clearly”

I think the code is the best explanation of the problem !

Answer 1

NSTimer relies on a running NSRunLoop to function. Your program terminates immediately after you create and schedule the timer, and an NSRunLoop is never set up anyway. Typically, in a Cocoa app, the call to NSApplicationMain() in main() sets up up the main run loop and begins “spinning” it. You should create a new project using the default Cocoa app template in Xcode, and create your timer in the NSApplicationDelegate’s -(void)applicationDidFinishLaunching: method.